The focus of this project is development and refinement of statistical procedures for the design and analysis of screening, detection, and related studies in cancer. Statistical problems under investigation include sample size determination, comparison of analysis methods, and development of stopping rules for screening trials. Each of these problem areas is common to screening and prevention trials in which the Division participates, but the methods for screening studies must address the special lead time and length biases inherent in screening programs. The research includes investigation of techniques to estimate and adjust for screening biases in the analysis of survival data, and the study of the relationship between long-term mortality and short-term outcome measures, such as stage shift. Probabilistic models of disease and screening are being developed to aid in the interpretation and evaluation of data from screening programs. A breast cancer screening model relating doubling time to survival is under derivation in collaboration with the Biostatistics Branch, DCE. Characteristics of case-control studies in the context of screening evaluation are also being considered.